Issue No. 76

The Orbital Index

Issue No. 76 | Aug 5, 2020

🚀 🌍 🛰

Starship SN5’s maiden flight. First, go watch the video (and also this one). Yesterday, after an aborted attempt on Monday at T-0 due to a turbopump spin start valve not opening, and another scrub in the morning, the single-engine Starship successfully completed its first flight to 150 m, including the use of new fold-out landing legs. Carrying a mass simulator in place of a nose cone, SN5 thoroughly resembled a flying grain silo. The 150 m hop is the first flight since Starship’s now-diminutive predecessor, Starhopper, made a ~150 m hop last August (video). Next steps include more short hops, a 20km flight, and the addition of two more Raptor engines. While this flight is a small step in the development of Starship, it may be looked back on as an important moment in the development of the first rocket specifically built for flying humans to Mars.

Perseverance. Perseverance launched last Thursday morning aboard its Atlas V and joined UAE's Hope & China’s Tianwen-1 on a ~7 month journey to Mars—with ExoMars delayed until late 2022, ¾ ain’t bad. We’re not going to go deeply into Perseverance this week since we’ve covered it so much already, including how it differs from Curiosity and of course its helicopter drone, which is set to be the first aerodynamic flight test on another planet. We’ve also discussed Perseverance’s sample collection mission in which it will gather samples in 43 ultra-clean sample tubes and cache them on the surface for a future sample return mission. Andrew recently read “The Design and Engineering of Curiosity: How the Mars Rover Performs Its Job” by the Planetary Society’s Emily Lakdawalla. Here are some highlights:

  • Mars Science Laboratory (MSL, the official name of Curiosity) was the most complex mission ever launched beyond Earth. Perseverance takes it even further.
  • Mars is really hard to land on, with too much atmosphere for purely retropropulsive landing and too little atmosphere for a parachute-only landing.
  • NASA wanted a tighter landing target ellipse than Viking, so they needed autonomous descent guidance. Curiosity’s final ellipse was 20km x 7km vs Viking’s 300km x 100km. Meanwhile, Perseverance adds autonomous Terrain-Relative Navigation.
  • Curiosity touched down on the Martian surface moving at 0.6 m/s, slower than the planned 0.75 m/s. This error was caused by unaccounted for variations in gravity of just 0.1% due to the local terrain. Had this error happened in the other direction—speeding up the descent—it could have damaged the rover’s mobility system.
  • The 26 samples (with map) that Curiosity has gathered as of July 2020.

Welcome home, Bob and Doug! After 64 days aboard the ISS, Astronauts Behnken and Hurley returned home aboard their Crew Dragon capsule. They also brought home the flag left at the station by the last Shuttle mission (STS-135) which Hurley, fittingly, had piloted. The capsule, parachutes, and flight data will now be analyzed for about six weeks to complete final certification—this should allow Crew-1 to depart as soon as late September with one JAXA and three NASA astronauts aboard (piloted by Behnken's spouse, Megan McArthur). After post-mission testing, the Demo-2 capsule will be refurbished for another flight in Spring 2021. This was the first US crewed splash down since the last Apollo-era flight in 1975 (the Apollo-Soyuz Test Project). It managed to avoid Tropical Storm Isaias, but not sightseers.

Guest Author Contribution

Rovers In Pike Place Market, Seattle. ☂️ First Mode is one of the companies playing a part in Perseverance’s success. The Seattle-based design and engineering company was founded by ex-engineers from Planetary Resources Inc. (now ConsenSys) and originally focused on asteroid mining techniques. They’re now developing both on- and off-planet projects including sustainable mining on Earth, the Intrepid Moon Rover, and a “Faux-ver” of Perseverance. A Faux-ver is a surrogate for a rover, matching it’s mechanical properties and built to assist during development and testing. This Faux-ver will play a key role in Perseverance’s entry to Mars, the “phase of the mission that’s known as EDL (entry, descent, and landing) or the ‘seven minutes of terror.’” They’ll be running all readiness tests for the 45 minute EDL remotely due to the pandemic. Although the Faux-ver isn’t intended for off-planet excursions, First Mode’s Intrepid rover will be. Here’s a short, insightful interview on the Intrepid Moon Rover and the value of going back to the Moon. The primary goal for Intrepid is to investigate the lunar surface to help find a site for sustained human presence on the moon as part of the Artemis Program. Intrepid will hopefully reveal details about the lunar magnetic field anomalies in the Reiner Gamma region (sometimes called the Lunar Swirl—pretty sick name, right?), and also survey a series of volcano-like landforms, as well as plateaus and craters which are thought to have pyroclastic or lava flow based formations (proposed route map below). Intrepid is about half the size of Curiosity (and Perseverance), but has the goal of running much farther and exploring much more of the Moon’s surface. (Tangentially: If you’re curious about how First Mode folks went from asteroid mining to rovers and faux-vers, they auctioned off a ton of neat hardware and tooling from their Planetary Resources days, prior to the merger, including a TVAC for $9,100.)

{Short blurb by Amreeta; opinions are my own}

First Mode’s planned route for Intrepid

News in brief. Virgin Galactic released images of VSS Unity’s fancy, 6-person cabin; the FCC approved (pdf) Amazon to launch 3,236 Project Kuiper satellites, a project to which Amazon is committing $10 billion USD; a Russian Proton-M vehicle launched two GEO communications satellites; Astra will likely attempt their first orbital launch of their Rocket 3.1 vehicle this week after two recent scrubs; Starlink-9 might finally launch after being delayed 10 times; Japan’s ispace revealed final plans for their HAKUTO-R ‘Mission 1’ lunar lander; and, Space Camp is in need of a capital infusion to avoid closing due to the pandemic—it has hosted nearly 1 million students over the years.

Tianwen-1’s navigation camera caught a double crescent shot of the Earth and Moon receding into the distance.

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